1. Field of the Invention
The present invention provides arrays of oligonucleotide probes immobilized in microfabricated patterns on chips for analyzing a cystic fibrosis transmembrane conductance regulator (CFTR) gene.
2. Description of Related Art
There has been considerable interest in developing genetic tests for genes responsible for disorders such as cystic fibrosis. Major pathologies associated with cystic fibrosis occur in the lungs, pancreas, sweat glands, digestive and reproductive organs. The gene associated with cystic fibrosis, CFTR, is a large gene with complex mutation and polymorphism patterns that pose a significant challenge to existing genotyping strategies. The CFTR gene has 27 exons, which span over 250 kb of DNA. Over 500 mutations of various types (transitions, transversions, insertions, deletions and numerous polymorphisms) have been described.
Because the characterized CFTR mutations are widely distributed throughout the gene, existing genotyping assays focus only on the most common mutations. Some methods rely on using PCR to amplify regions surrounding mutations of interest and the characterizing the amplification products in a second analysis step, such as restriction fragment sizing, allele specific oligonucleotide hybridization, denaturing gradient gel electrophoresis, and single stranded conformational analysis. Alternatively, mutations have been analyzed using primers designed to amplify selectively mutant or wildtype sequences. None of these methods readily adopts to monitoring large regions of the CFTR gene, identifying hitherto uncharacterized mutations or simultaneously screening large numbers of mutations with a high degree of accuracy.
The development of VLSIPS.TM. technology has provided methods for making very large arrays of oligonucleotide probes in very small areas. See U.S Pat. No. 5,143,854, WO 90/15070 and WO 92/10092, each of which is incorporated herein by reference. U.S. Ser. No. 08/082,937, filed Jun. 25, 1993, describes methods for making arrays of oligonucleotide probes that can be used to provide the complete sequence of a target nucleic acid and to detect the presence of a nucleic acid containing a specific nucleotide sequence. Others have also proposed the use of large numbers of oligonucleotide probes to provide the complete nucleic acid sequence of a target nucleic acid but failed to provide an enabling method for using arrays of immobilized probes for this purpose. See U.S. Pat. No. 5,202,231, U.S. Pat. No. 5,002,867 and WO 93/17126.
Microfabricated arrays of large numbers of oligonucleotide probes, called "DNA chips" offer great promise for a wide variety of applications. The present application describes the use of such chips for inter alia analysis of the CFTR gene and detection of mutations therein.